1. Field of the Invention
The present invention relates to an insulation-displacement terminal fitting and to a method for producing an insulation-displacement terminal.
2. Description of the Related Art
A known insulation-displacement terminal fitting is disclosed in Japanese Unexamined Patent Publication No. 8241740. This terminal fitting has pairs of inwardly facing blades formed on opposed side walls. A wire can be pushed between the blades in each pair so that the blades cut a resin coating of the wire and contact a core of the wire. Each blade is V-shaped when viewed in a direction in which the wire is pushed, and is formed by bending a portion of the flat side wall into V-shape.
The blades of the prior art insulation-displacement terminal fitting are formed by embossing portions of the side walls into a V-shape. More particularly, the side walls are extended by placing a pressing jig at a position which becomes the apex of the V-shaped blade. Thus, the thickness of the blade becomes gradually thinner toward the apex. As a result, the apex of the blade may crack or split.
A crack or split may be avoided by embossing the side walls to a smaller degree, and thus widening a spacing between opposed blades, or by making the insulation-displacement terminal fitting of a relatively soft material. The former option cannot accommodate thin wires, while the latter option may cause a deformation and/or an insufficient contact pressure during insulation displacement. Neither option can solve the above problem.
In view of the above, an object of the present invention is to prevent cracks or splits in blades when side walls of an insulation-displacement terminal fitting are deformed to form blades.
The subject invention is directed to an insulation-displacement terminal fitting with a pair of side walls extending from a bottom wall. Portions of the side walls are bent to form at least one pair of blades, and a wire can be pressed at least partly between the blades for connection therewith. At least two slits are formed along boundaries between the bottom wall and the side walls and in areas that correspond at least to an entire forming area of the blades. According to a preferred embodiment, the blades are substantially V-shaped.
The insulation-displacement terminal fitting also includes a bent portion in the bottom wall and within a forming area of the slits.
The blades are formed by bending the side walls at the same time that the bent portion is formed in the bottom wall, but preferably after the slits are formed along the boundaries between the bottom wall and the side walls. The operation of forming the blades brings base ends of the blades closer to each other in the side walls. Simultaneously, an operation of forming the bent portion brings base ends of the bent portion closer to each other in the bottom wall. The shortening of the bottom wall due to the formation of the bent portion preferably is substantially equal to the shortening of the side walls due to the formation of the blades. Accordingly, neither the blades nor the bent portion undergo an extensional deformation and cracks and/or splits can be avoided.
The bent portion preferably is in a position on the bottom wall to contact an end portion of the wire. Thus an end face of a properly positioned wire contacts the bent portion without bending the wire. However an improperly positioned wire is bent upward by the bent portion.
The insulation-displacement terminal fitting may be inserted into a connector housing and locked by a retainer, and an end face of the wire mounted in a proper contact position may be in proximity to the retainer. However, the wire may be mounted in an improper contact position that is displaced toward the front of the terminal fitting from the proper contact position. In this situation, the retainer may interfere with the end of the wire, and may cause an assembling error if the insulation-displacement terminal fitting is mounted while being left displaced. However, in the present invention, the end of a wire that is mounted in an improper contact position interferes with the bent portion and is deformed, which enables detection of the wire in the improper contact position due to the deformation of the wire.
The invention also is directed to a production method for forming an insulation-displacement terminal fitting. The method comprises forming slits along an area between a bottom wall and a pair of side walls. The method then comprises bending portions of the side walls to form at least one pair of blades, such that a wire can be pressed at least partly between the blades and connected therewith. The blades preferably are formed to have substantially a V-shape.
The production method further comprises a step of forming a bent portion in the bottom wall for contacting a front portion of the wire. Preferably, the bent portion is formed within a forming area of the slits.
During the bending step of the blades, front and rear base ends of the respective blades are brought closer to each other in the side walls and simultaneously front and rear ends of the bent portion are brought closer to each other in the bottom wall. Additionally, a sum of the shortened distances between the base ends of the front and rear blades is substantially equal to a shortened distance between the base ends of the bent portion.
These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings.